diff --git a/js/xpconnect/src/XPCJSID.cpp b/js/xpconnect/src/XPCJSID.cpp
index 15e333917eeb..63cdc136117d 100644
--- a/js/xpconnect/src/XPCJSID.cpp
+++ b/js/xpconnect/src/XPCJSID.cpp
@@ -11,7 +11,6 @@
 #include "mozilla/Attributes.h"
 #include "mozilla/jsipc/CrossProcessObjectWrappers.h"
 #include "mozilla/StaticPtr.h"
-#include "nsIProgrammingLanguage.h"
 
 using namespace mozilla::dom;
 using namespace JS;
diff --git a/js/xpconnect/src/XPCWrappedNative.cpp b/js/xpconnect/src/XPCWrappedNative.cpp
index 84896475360b..3c6be7839a34 100644
--- a/js/xpconnect/src/XPCWrappedNative.cpp
+++ b/js/xpconnect/src/XPCWrappedNative.cpp
@@ -8,7 +8,6 @@
 
 #include "xpcprivate.h"
 #include "mozilla/jsipc/CrossProcessObjectWrappers.h"
-#include "nsIProgrammingLanguage.h"
 #include "nsWrapperCacheInlines.h"
 #include "XPCLog.h"
 #include "jsprf.h"
diff --git a/xpcom/build/XPCOM.h b/xpcom/build/XPCOM.h
index 96c3dacac865..01a959d6cc7d 100644
--- a/xpcom/build/XPCOM.h
+++ b/xpcom/build/XPCOM.h
@@ -85,7 +85,6 @@
 #include "nsIObserverService.h"
 #include "nsIOutputStream.h"
 #include "nsIProcess.h"
-#include "nsIProgrammingLanguage.h"
 #include "nsIProperties.h"
 #include "nsIPropertyBag2.h"
 #include "nsIRunnable.h"
diff --git a/xpcom/threads/nsThread.cpp b/xpcom/threads/nsThread.cpp
index 6fb0e11b1469..52ac1ca2de80 100644
--- a/xpcom/threads/nsThread.cpp
+++ b/xpcom/threads/nsThread.cpp
@@ -16,7 +16,6 @@
 #include "nsMemoryPressure.h"
 #include "nsThreadManager.h"
 #include "nsIClassInfoImpl.h"
-#include "nsIProgrammingLanguage.h"
 #include "nsAutoPtr.h"
 #include "nsCOMPtr.h"
 #include "pratom.h"